These proceedings contain the papers presented at the 3rd Workshop on the Use of Computational Methods in the Study of Endangered languages held in Hawai’i at Manoa, February 26–27, 2019. As the name implies, this is the third workshop held on the topic — the first meeting was co-located with the ACL main conference in Baltimore, Maryland in 2014 and the second one in 2017 was co-located with the 5th International Conference on Language Documentation and Conservation (ICLDC) at the University of Hawai‘i at Manoa. The workshop covers a wide range of topics relevant to the study and documentation of endangered languages, ranging from technical papers on working systems and applications, to reports on community activities with supporting computational components. The purpose of the workshop is to bring together computational researchers, documentary linguists, and people involved with community efforts of language documentation and revitalization to take part in both formal and informal exchanges on how to integrate rapidly evolving language processing methods and tools into efforts of language description, documentation, and revitalization. The organizers are pleased with the range of papers, many of which highlight the importance of interdisciplinary work and interaction between the various communities that the workshop is aimed towards. We received 34 submissions as papers or extended abstracts. After a thorough review process, 12 of the submissions were selected for this volume as papers (35%) and an additional 7 were accepted as extended abstracts which appear in Volume 2 of the workshop proceedings. The organizing committee would like to thank the program committee for their thoughtful input on the submissions. We are also grateful to the NSF for funding part of the workshop (award #1550905), and the Social Sciences and Humanities Research Council (SSHRC) of Canada for supporting the workshop through their Connections Outreach Grant #611-2016-0207. We would moreover want to acknowledge the support of the organizers of ICLDC6, in particular Gary Holton, Brad McDonnell and Jim Yoshioka.